In the personal audio delivery systems, there have been many different methods to juxtapose a speaker next to the ear canal. The traditional headphone (“over head”) has a plastic or metal headband across the top of the head with speakers encased in plastic on either side. The cord for the traditional headphone protrudes from either both speakers or just one speaker and is worn on the front of the individual. Newer designs for headphones include a plastic band that is worn across the occipital portion of the head (“behind head”), connecting the two speakers with a wire that could be worn on the front or the back. There are also the in-ear headphones (“earbuds”) with wires from both speakers that may be worn inside the ear canal.
None of these common personal audio delivery systems are very comfortable when worn during sleep. The problem with the “over head” and “behind head” headphones is that they use a hard material like plastic or metal to hold the shape. The individual wearing headphones to sleep would not be able to lie on the back with the “behind head” design, and lying on the side would be extremely uncomfortable with either design due to the bulk of the plastic or metal-enclosed speakers. They are unlikely to stay in place for an extended period of time with normal sleep head movements. The “earbuds” design may stay on better, but is often irritating to the soft ear cartilage. When they are worn for an extended period of time, the hard components may actually cause ulcers in the thin skin of the ears, and an inability for the ear canal to be ventilated may predispose the wearer to fungal or bacterial ear canal infections.
U.S. Pat. No. 7,202,774 to Hoyle discloses an eye shield sleeping device including a pair of speakers. The speakers are attached externally to an elastic strap to cover a user's ears. The device disclosed in Hoyle is however intended for naps, such as while traveling or at work, and it is not suitable for extended sleep. For example, the size and means of attachment of the speakers are not amenable to different sleep positions (e.g., lying on one's side) and sleep movements.
Personal audio delivery systems are necessary for the effects of a phenomenon of brainwave entrainment through binaural beats. There are various brainwaves from gamma (γ, 26-100 Hz) to delta (δ, 4 Hz), which represent a spectrum from awake and concentrating to deep sleep, respectively. The brain can be entrained to certain brainwave patterns by the delivery of sounds to the ears. More precisely, when two tones of a similar pitch are delivered to the individual ears, the brainwaves may then take on the pitch frequency difference. Meanwhile, because the 2 tones are so similar, the conscious mind will not sense this pitch difference. For example, when a 210 Hz frequency tone is presented to the right ear, and a 200 Hz tone is presented to the left ear, the superior olivary nucleus of the brain will integrate these two tones and induce a 10 Hz brainwave. A 10 Hz brainwave is generally an alpha (α, 8-12 Hz) wave, which corresponds to a state of relaxed consciousness. This third brainwave frequency is considered the binaural beat, which has occurred through the sound delivery to the two ears.
Therefore, brainwaves can be entrained to take on a certain pattern via the delivery of specific tones to the ears. With the right audio sounds, the brain can be “programmed” to fall asleep or to wake up. Note that the sounds must be in stereo and be presented to the ears distinctly, not mixing in the air before entering the ear canals. This principle is called “stereo separation.” Thus, the binaural beat effect can only be produced by wearing personal audio equipment, such as headphones. For one to sleep using binaural beats, one must wear a personal audio delivery system, and comfortable equipment would of course be preferred.
Some systems for varying the brain state and/or inducing states of consciousness using binaural beats are known. See, e.g., U.S. Pat. No. 5,135,468 and U.S. Pat. No. 5,356,368. However, these prior systems simply employ conventional speakers or headphones. As such, the prior art systems are not suitable for extended and comfortable sleep.
It is therefore desired to provide a sleep aid system with headphones that are comfortable enough to sleep in all night long.